Variable condenser and apparatus for operating and supporting the same



Oct. 31, 1933. c, M. WILCOX 1,932,498

VARIABLE CONDENSER AND APPARATUS FOR OPERATING AND SUPPORTING THE SAME Filed Nov. 23, 1931 5 Sheets-Sheet 1 Oct. 31, 1933. c. M. WILCOX ,4 8 VARIABLE CONDENSER AND APPARATUS FOR OPERATING AND SUPPORTING THE SAME Filed Nov. 23, 1931 3 Sheets-Sheet 2 c. M. WILCOX 1,932,498 VARIABLE CONDENSER AND APPARATUS FOR OPERATING AND SUPPORTING THE SAME Filed Nov. 23, 1931 5 Sheets-Sheet 3 k? as 2a a 35C. .3 Z6

' Patented Oct. 31 1933 VARIABLE CONDENSER AND APPARATUS 50R OPERATING SUI PORTING THE i Chester M. i Wilcox, Charlotte, .Mich, assignor to General Apparatus Corporation,

a corporation of rNew York New York, I

Application November 23, 1931 Serial No. 578,633

v Claims.

a means for supporting and operating the same.

* operating elements values of capacity so 1 structed as toenclose ports for the insulating One of the chief objects'oi my invention is to provide a. variable condenser structure of 'the sliding type with the necessary supporting and of the device operate with a minimum of friction.

Another object of my invention is to provide a variable condenser structure of the sliding type in which the movable plates thereof may be easily aligned to accurately interleave with the stationary orthis alignment during long periods 01 use.

Another object of my invention is to an improvedcondenser struct driving mechanism for transforming rotary movement of an operating control shaft into linear movement mechanism being capable of providing a continuously variable ratio between the movement of the operating control shaft and the slidable movements of the shiftabl'e condenser plates, the rate of change of this. ratio being controllable between widelimits at all points in the adjustment of thestationary plates.

Another object of my invention is to provide a variable condenser of compact construction and small size and having at the same time com-1 paratively low minimum and high maximum that such condenser will not sacrifice the desirable features of larger conclensers. o

Another object of my invention is to provide for a variable condenser of the sliding type an inexpensive but relatively emcient and veryrigid frame construction;

. Another objector my invention is to provide a variable condenser oi the sliding type with eilicient and economical design of frame so conthe conducting elements of the condenser,- thus shielding them from electro-magnetic and electro-static coupling, such frame also furnishing, rigid and convenient supmembers which in turn hold the assembly of the stator plates.

Another object of my invention is to provide a method of economically assembling moving and stationary plates in which rigidly supports ,said'plates in accurately spaced alignment.

Another object of my invention is to provide an inexpensive and practical design of variable conin which the moving elements specification, the novel 'plete condenser.

stator platesandto maintain w of the rear cover plate 0 to disclose .details of "apparatus on the interior.

1 'Fig. 3 is an end elevation view of the condenser.

provide" ure with a simple of the condenser plates, said" a form of construction denser utilizing rectangular plates of smalldimensions thereby minimizing 4 the eifect of irregularities or defectsin plate mountings and lack of flatness in the; material of which the I I Platesaremade. r r,

The above and; other objects willbeapparent from the following description ofthe'preferred form of the invention, reference being had to the accompanying drawings forming ag-part otthe features being set forth 3 in the appended claims. In the said drawings: t Fig. l is a 'front elevational view of the comthe same with a portion '70 thecasing broken away construction of condenser I Fig. 2 is a rear view of.

cover and a condenser unit magnetic shieldshown 8O in section in plate form two units. 7 1

Fig. 6 is a cross section taken on line 5-5 of Fig. 2 looking in the direction indicated by the arrows. Y t

Fig. 6 is a detached plan view of the drive disk.

Fig. 7 is a longitudinal section taken on line l-'7 of Fig. 2 looking in the directionlndicated by the arrows. I

Fig. 8 is a detached plan view of the channel shaped condenser plate carriage, shown also-in section in Figs. 4 5 and '7; I

Like numerals refer to like parts throughout the several views. t

The frame consists of the two end plates 13 -14. into which the channel shaped member com prising the front plate 10 and the integrally formed top and bottom plates 11, 12; by means of and located between the the integral tongues 15, 16, is mortised and swaged thus forming a box type I adaptable to quantity production; being ofchannel form is hence very rigid; it forms an electromagnetic and electrostatic shield for the conducting portions, and it protects the mechanism from s mechanical damage and dirt; whereas frames for. sliding type condensers have in the past been of different construction usually consisting of an assembly of plates or bars which in all cases lacked one or more of the features obtained by my construction.

A channel shaped carriage member 22 (Fig. 8) adapted to support one or more moving condenser plate assemblies is located within the frame. Opposed parallel runways 23 extending the length of the carriage are pressed into its top and bottom turned edges 26, 27. Corresponding, comparatively short runways 24 are pressed into the top and bottom portions 11, 12 of the frame, these being only of sufficient length (one half the movement of the carriage plus the diameter of the ball) to permit the desired movement of the sliding carriage member 22, and are located as near the ends of the condenser frame as practical without permitting the escape of the balls 25 (Fig. 5). These balls operate in the runways between the frame and the moving carriage as indicated. The carriage 22 is of elastic or spring materialand the top and bottom grooved portions 26, 27 press outwardly against the balls. The balls operating in the runways support the sliding carriage accurately in place within the frame and limit its movement to a substantially straight line. This construction reduces friction between the sliding carriage and the frame to a minimum and it provides a method of holding the sliding carriage in alignment that is entirely without play. Wear upon bearing points is taken up by the spring in the flexible sides of the carriage and since the bearing points are opposed no change in alignment will occur from the effect of the wear at the bearing points. This method of supporting the sliding carriage is inexpensive, easily assembled and requires no adjustment, whereas previously used constructions have usually utilized a plate sliding between bars in a groove or some equivalent, and have had few if any of the advantages mentioned.

Ball bearings are shown as the rolling memhere but it is understood that equivalents such as rollers either fixed or stationary are also covered by my invention.

The moving and stationary plates 28 used in this condenser are alike and may be duplicates, are individually small in area, and are held in spaced alignment for strengthening purposes by channel shaped mounting plates 29, 30 into which they are mortised and swaged. They are held in accurately spaced'alignment at an additional point on their outer peripheries by the spacing ties 31 into which they are also mortised and swaged. 1n the case of the stationary plates there is attached to each end of the mounting plate 30 an insulating member 32 which is in turn supported by brackets 33 formed from the sides 11, 12 of the frame. These rackets being integral with the frame member are rigid, accurate, inexpensive, and form an improved method of supporting forming a direct the stationaryplate assembly. y

From the material of which the mounting plate 30 is made, are formed soldering lugs 34 thus contact to the mounting ,plate at a point convenient for attachingcircuit wires by soldering and solderin lug.

In themounting of the moving plate assemblies on thesliding carriage 22 the side flanges of the channel shaped mounting plates 29 fit accurately on each side of bars 35 contained in the bottom of the sliding also saving the cost of a'separate the integrally formed cross mem-,

carriage. Lugs 36, formed from the material of the mounting plate 29, extend through openings 37 in the bottom plate of the carriage 22 and when clinched hold. the assembly in place thereon. These constructions are improved methods of accurately aligning and holding moving plate assemblies to the carriage.

Rectangular openings 38 are cut in the sliding carriage 22 corresponding with the positions of the stator plates when the moving plates 26 are entirely withdrawn from their closed and overlapping relation to the similar stator plates thereby increasing the distance between the stator plates and any conductor at moving plate potential, thus decreasing the minimum capacity at that minimum position.

The relative positions, as well as the shape and the direction of movement of the plates described in this condenser will produce a linear capacity change in direct proportion to the movement of the, plates. Such a condition makes easy matching of synchronously operated condenser units.

In practical use, particularly for use in radio sets,

it is desirable to have the rate of change of capacity in respect to control knob 50 and dial movement as indicated by dial 51, a variable factor, thus making the movement of the control knob proportional either to the frequency or wavelength as may be desired of the electrical circuit with which the condenser is designed to be associated. Plates have been made of shapes to produce this desired result or an approximation thereof but at the cost of waste space and lack of rigidity. My invention provides a method of securing at all points of the condenser adjustment a proper and predetermined rate of change of capacity in respect to dial movement. This will be seen by reference to the drawings, Figs. 5, 6 and 7 in which disc 60 is mounted in a rotatable position on the condenser frame 10 by means of shaft 61 to which it is fixed at the inner shouldered and upset portion of the shaft, and is held in spaced relationship from the frame by washer 62 which being of suitable absorbent material as of felt, carries a lubricant for the bearing, and is held in position by a curved tension spring 63. Attached to shaft 61 by sleeve 80 is a scale disc 64 held between plates 90, 91 arranged by suitable markings thereon to indicate in connection with point 65 the relative movement of the disc 64. Attached to frame 10 is a bracket 66 which forms a supporting bearing for shaft 69 which, at its inner end is provided with the slightly separated spring friction plates '70, '71 adapted to engage the periphery of the disc 60. The shaft 69 may have a handle or knob 50 for turning the shaftto operate the disc in adjusting the condenser carriage. Other means of driving this disc may however be employed.

A spiral slot '12 is cut in disc 60 and the contour of this slot or cam 72 will depend upon-the rate of change of capacity'desired at the various points of condenser movement. Operating in enhold the pin in contact with one if desired a spring 74 (Fig. 1), may

i 1 6 to secure excellentresults when-the apparatus is association with radio receiving apparatus.

' no limitations on my invention Y g -s p f the-appended claims .-r"c1aim ed to Support stator said stator plates on the frame body member. 3. In a [variable condenserthe combination with: a channel shaped body member provided of resilient sheet metal, 3 formed thereon for co-operating with grooves of the carriage,

I formed in c a ew m m a w i 1,032,498 j movement and rate of change of theplates may 7 --be varied or regulated'according to any desired variable: rate; to be,v predetermined in the of the oam slot '72, the approximate shape of which should beverynear to that shown in Fig.

utilized in the ordinary manner in Many variationsof the particular construction described for radio "andother analogous purposes f within the I art are possible and I desire that it be understood ordinary skill of those skille'din-the that modificationsmay be'made and that I intend other than: those plates forming a box type frame and being adaptcondenser plates, a moving 1 f; #1 member of channel'form adapted to support mov- *I able condenser plates mounted within said frame and supported by said frame in a'manner per-Q m'itting: only substantially straight 1 line movement jthereof in relation to-said frame.

;2., In'a variablecondenser of the sliding platetype, theoombin'ationwith a channel shaped body member, of a pair of end plates secured thereto for. forming a box type frame, means on the channel shaped member for securing thereto a plurality of stator-plates arranged in spaced rela- I tionship-with each other, a channel shapedmov ing member'formed of resilient sheet metal, antifriction devices interposed nel shaped moving member and the channel "shaped body'memb'er of the ity of spaced apart condenser plates carried by' between said chanframe, and a pluralthe' moving memberj and interleaving withthe witha pair of end closure plates forming a box 'typeframe, aplurality of projections formed'integrally on said channel shaped member, -a plu-' 'rality of insulating members attached to said integral projections,

w a mounting plate attached to said insulating members, a plurality of spaced apart "stator plates supported by said mounting .plates a moving member v mounted within said frame, comprising a channel shaped body formed there being grooves formedin the walls of the channel shapedbody member,anti-friction devices within said grooves,

and a plurality of movable condenser plates so cured upon the movable-member and interleaved withthe said stator plates on the said body member.

' In a variable condenser the combination a supporting frame in the form of -a box-like structure, a carriage element mounted for longi- .tudinal movement within the frame and consistpermit {movement of the carrelation to the frame, the bottervals to form cross members between the sides a condenser leaf mounting plate of channel form adapted to receive within the said channel portion thereof, the cross members the carriage element, there being a ay utcondenser v 7 receiving said lugsof I l, A variable condenserconstruction compri'slngin combination a pair of end plates, at chan-x nel shaped body member connecting said end combination, a hollow, box-like frame,

said mounting plate in alignment with theopenings in said carriage element thereby providing carriage, and aflxedly attached in spaced relationship with each other to said channel shaped mounting; plate.

In a variable condenser the combination with a frame, a moving element comprising a'carriage of channel-like shape formed from sheet metal,

a. mounting plate-a plurality of conducting plates securedin spaced relationship tosaid mounting plate, a plu'ralityjof lugs formed from the material of said mounting plate, therebeing aplurality' of openingsv in the'said carriagemember for the mounting plate whereby to hold said mounting plate and said conducting platescarried therebyin alignment with said carriagemember.

6. Inc. variable condenser of the type having elements variably "inter-leaved by substantially relative straight line movementathe combination of a frame, a plurality of insulating members attached to said frame, a plurality of stationary conducting plates held in spaced relationship insulating members to" said frame, a plurality of moving conductor plates held in spaced relation- I .Sh p to each other, a movable carriage supporting j said movable plates and mounted" for sliding L movements on the frame, to provide substantial straight line movements for interleaving said moving plates with said stationary plates, the moving carriage form of sheet metal and being providedwlth an opening adapted to underlie said stationary condenserfiiplates when the movin'g carriage isoperated to separate the-movable plates from the stationarynplates for the 'purposeof decreasing the electrical capacity between the said stationary plates and said carriage member.

7, A variableigang condenser comprising, in

combination, a hollow, box-like frame,'having oppositely disposed, I relatively rigid faces, ball races carried by said faces, a carriage mountedmov within said frame .and having oppositely disposed, resilient faces, ball races carried by said resilient faces, said frame, carriage andraces being'formedto provide for movement of said carriage parallel to itself anti-friction bearings interposed in said races, a plurality of groups-of stator. plates I secured to said frame, and a plurality. of groups of moving plates secured to said carriage and forming condensers, the relation 30 a plurality of variable of said plate groups being so chosen that move- -ment of said carriage varies the capacity of said condensers simultaneously and similarly.

8. A variable-gang condenser comprising, in

only of said carriage within said frame, antifriction bearings positioned in said races, a plurality of groups of stator plates secured to said frame, and a plurality of groupsof movable plates secured to said carriage, said groups denning a'plurallty 'of variable condensers, and the v 3- plurality of, lugs pressed from the material of with no respect to each other and being securedby said being in, substantially channel within said frame, and 1 having 335 oppositestator and moving plate groups being so positioned with reference to each other that movement of said carriage varies each of said condensers simultaneously and similarly.

9. A variable gang condenser comprising, in combination, a hollow, box-like frame, having oppositely disposed, relatively rigid faces, ball 'stituting a variable condenser, and means for moving said carriage in said frame whereby said condensers are varied simultaneously and similarly.

\ 10. A variable condenser comprising, in combination, a box-like frame, comprising a U-- shaped member and end plates secured thereto, a carriage nesting within said frame, comprising a second U-shaped member, anti-friction bearings positioned between the outwardly extending arms of said U-shaped members, stator plates mounted within said frame and extending longitudinally thereof, moving plates mounted in said carriage and extending longitudinally thereof for intermeshing engagement with said stator plates, and means extending through said frame for causing longitudinal movement of said carriage within said frame.

CHESTER M. WILCOX. 

